The Pros And Cons Of Biodiesel

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1. Introduction To date, biodiesel production has received considerable attention as a biodegradable and non-polluting fuel. It is the perfect substitute to replace fossil fuels which are likely to run out within a century. Apart from the difficulty of meeting the high energy demand, the environmental issues concerned with exhaust gases which give rise to the greenhouse effect by the usage of fossil fuels also encourage the usage of biodiesel which has proved to be way more environmental friendly than fossil fuels. Following this, biofuels such as biodiesel are believed to be the future fuels to play an important role in transportation sector instead of liquid fossil fuels. 文献7 Biodiesel is a liquid fuel, the properties of combustion quite…show more content…
However, non-catalytic trans-esterification mechanism could only react at supercritical condition which requires higher temperature and pressure therefore increase the parasitic energy. Considering the specific condition, the most commonly used method for trans-esterification is catalytic method which carries out at low temperature and pressure. There are 3 different type of catalytic trans-esterification: homogeneous, heterogeneous, and enzymatic. More specifically speaking, for homogenous catalysis, we have 3 different catalysts which are basic, acidic, and enzymatic. Here, Table 2 gives the advantages and disadvantages of homogeneous catalysts compared to the other two catalysts. 文献7 Table 2: Comparison of homogeneous, heterogeneous and enzymatic catalysis for biodiesel production. 文献7 2. Biodiesel…show more content…
It requires only low temperatures and pressures and producing a high conversion yield. [] Scheme 6 shows the mechanism of the base-catalyzed transesterification of vegetable oils. Firstly, alcohol is mixed with the basic catalyst to produce an alkoxide and the protonated catalyst. Secondly the nucleophilic site of alkoxide attacks the carbonyl group of the triglyceride, producing a tetrahedral intermediate. Then the alkyl ester and the corresponding anion of the diglyceride are formed from the tetrahedral intermediate. Finally, deprotonates the catalyst, thus regenerating the active species. [] This process repeats 3 times in order to obtain alkyl esters and

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